Such a circuit breaker, also called a compressed gas-blast circuit breaker, is used especially in power distribution networks. It is designed in such a way that in the event of a separating of the contacts, or in the case of a short circuit, an arc is blasted with gas and consequently quenched as quickly as possible. The gas which is used most for this purpose is SF6 (sulphur hexafluoride).
A circuit breaker of the type referred to in the introduction is described in DE 4211159 A1 and U.S. Pat. No. 5,589,673 A. In the case of this circuit breaker, a pressure chamber, in which the arc is created, is connected in a valve-controlled manner to a compression chamber. The compression chamber is connected to a low-pressure chamber via an overpressure valve and a replenishment valve. The valves are arranged in a ring-like and abutting manner with an overlapping zone. The overpressure valve, on the low-pressure chamber side, is pressed by a spring against a valve holder in the direction of the compression volume. Gas can therefore flow from the compression volume into the low-pressure chamber only when its pressure is higher than the spring force. This type of construction, however, is relatively complicated and requires a large number of elements.
A circuit breaker of the type referred to in the introduction is also described in the earlier European application 09170549.1, the publication of which was provided on Mar. 3, 2011 with publication number 2299464.
EP 2270828 A1 furthermore describes a high-voltage power circuit breaker which is constructed as a self-blast circuit breaker, in which a check valve is arranged between two volumes of its extinction chamber. This valve has at least one small metallic, flexible plate which can move between a valve seat and a stop of the valve within its elastic deformability. The valve is designed so that with opening of the circuit breaker it enables the feed of compressed, cool gas from a compression volume into a heating volume which is subjected to the action of arc gases, but prevents hot arc gases flowing from the heating volume into the compression volume. Therefore, for the at least one small plate a material which can withstand temperatures of up to 2500° C. is used.
Reference is also to be made to EP 1939910 A1. This document discloses a compressed gas circuit breaker with a plurality of contacts which are movable in relation to each other. Arranged around a first contact is a blast volume which is connected via a blast passage to an arcing zone. The blast volume is isolated from a low-pressure chamber by means of a separating element. In the separating element provision is made for a throughflow opening which serves for the gas exchange between the blast volume and the low-pressure chamber.